Method for reinforcing loose rock and coal

ABSTRACT

A plastic foil container having two separate compartments filled with the components of a foaming mixture, is inserted into a bore drilled into loose and caving rock or coal, and broken by a pointed rod inserted into the bore so that after sealing said bore with a plug a foam mixture fills, expanding due to swelling pressure, the bore and surrounds loose and caving rock or coal and reinforces the rock after hardening, particularly when the rod is left in the bore.

United States Patent J ankowski et al.

[54] METHOD FOR REINFORCING LOOSE ROCKAND COAL [72] Inventors: AlfonsJankowski, Essen-Heisingen;

Otto-Ernst Glaesmann, Castrop- Rauxel; Gerhard Haake, Essen- Kray, allof Germany [73] Assignee: Bergwerksverband GmbH, Essen,

Germany [22] Filed: March 3,1971

21 Appl. No.: 119,822

[30] Foreign Application Priority Data March'4, 1970 Germany ..P 20 10140.0

[52] US. Cl. ..61/45 B, 52/741, 61/63 [51] Int. Cl. ..E21d 20/02 [58]Field of Search ..61/45 B, 63, 36, 35; 52/698,

[56] References Cited UNITED STATES PATENTS 3,430,449 3/1969 Novotny etal ..61/45 B 51 Oct. 17, 1972 Primary Examiner-Dennis L. TaylorAttorney-Michae1 S. Striker [5 7 ABSTRACT A plastic foil containerhaving two separate compartments filled with the components of a foamingmixture, is inserted into a bore drilled into loose and caving rock orcoal, and broken by a pointed rod inserted into the bore so that aftersealing said bore with a plug a foam mixture fills, expanding due toswelling pressure, the bore and surrounds loose and caving rock or coaland reinforces the rock after hardening, particularly when the rod isleft in the bore.

12 Claims, 4 Drawing Figures METHOD FOR REINFORCING LOOSE ROCK AND COALBACKGROUND OF THE INVENTION The method of the prior art has beensuccessful in coal mining when coal is deposited in steep seams. Also invery large gently sloping seams, the method has been successful forpreventing weak coal faces from loosen ing. For these purposes, thefoam-forming resin mixture is filled, before foaming, and only due tothe action of the force of gravity, into downward slanting bores inwhich the mixture, after closing of the bores, expands due to swellingpressure, and enters cracks and crevices, filling and sealing the same.Before the bores are closed, reinforcing rods, preferably made ofinexpensive wood, are inserted into the bore and reinforce the looserock. At the same time, the amount of the resin mixture required forfilling the bore is reduced, since part of the volume of the bore istaken up by the rod, which remains in the same after hardening of theresin mixture.

However, it is not possible to use this method to fill bores which arehorizontal or upward slanted, since the foam mixture would run out ofthe bore before filling process has been done. It has been proposed topump the components of the foam mixture separately into the bore in therock, and to mix the components directly before, or in the bore. It hasalso been proposed to insert a foam-forming resin mixture in mixedcondition by means of a pressure pump into the bore, but this method hasnot been found successful, since an apparatus for injecting the mixtureis expensive, and furthermore because the sealing and closing of thebores is difficult and also expensive.

If expandable probes are used for the pressure injection, a great partof the injected resin mixture flows out of the bore when the pressureprobe is exchanged for a plug closing the bore. The use of expandablepressure probes which remain in the bore, sealing the same, is also tooexpensive.

SUMMARY OF THE INVENTION It is one object of the invention to overcomethe disadvantages of prior art methods for reinforcing loose rock byfilling bores in the rock by a resin mixture, and to provide a newmethod permitting the filling of upward slanted bores in the rock.

Another object of the invention is to prevent the mixing of thecomponents of the foam-forming mixture before all components are in thebore.

Another object of the invention is to plug the entrance opening of thebore by a quickly hardening resin mixture, before the foam in the borehas hardened.

With these objects in view, a method of the invention comprises drillingat least one bore into loose rock; inserting into the bore at least onebreakable container having at least two separate compartments filledwith two components which form a resinous hardenable foam, when mixed;and breaking the container in the bore to establish communicationbetween the compartments.

As a result, the components mix in the bore to form a foaming mixturefilling, expanding due to swelling pressure, the closed bore and thesurrounding loose and caving rock and coal then hardening in the bore sothat the rock is reinforced.

Preferably, the breaking of the container is carried out by inserting apointed rod into the bore after insertion of the container, and it isadvantageous to use the rod for mixing the components, and to then leavethe rod in the bore for reinforcing the hardened foam mixture whichfills the volume of the bore not taken up by the rod.

Due to the fact that the components of the foamforming mixture areinserted into the bore separated by the walls of the container, whichpreferably consists of plastic foil material, bores which slant upwardor which are horizontal, can be filled by the: reinforcing hardenablemixture.

It is a particular advantage of the invention that the rod, which isusually inserted into "the bore for reinforcing the rock, can also beused for breaking the container in the bore. Very little equipment isrequired for carrying out the method of the invention, and the methodcan be practiced by unskilled workers.

For the foam-forming synthetic resin mixture used in the method of theinvention, polyurethanes with added water have been found advantageous.The properties of the hardened foam, and the reaction and hardeningtimes, can be easily varied by suitably selecting the ratios of thecomponents forming the mixture.

In the preferred embodiment of the invention, the container includes anouter tubular wall and an inner tubular wall in the outer tubular walland having the same length. Clips close the ends of both tubular wallsat the ends of the container. One of the compartments is formed in theinner wall which is filled by one component, and the other compartmentis formed within the outer tubular wall and around the inner tubularwall, and filled with the other component.

The tubular walls are made of synthetic plastic foil, which may consistof polyethylene, polypropylene, polyester, or polyamide. Double-walltubular containers of this type can be easily mass-produced, and arevery inexpensive. Although they are reliably holding the components ofthe mixture during transport, they can be easily destroyed in the borein the rock by a pointed wooden rod.

The following examples are illustrative, and not limiting for theinvention.

EXAMPLE I which is foamed by a propellant, as set forth in the followingexample.

EXAMPLE 2 A first component in the outer annular compartment within theouter tubular wall of the container, consists of 100 weight units of apolyester forming a dough with 200 weight units of rock powder. Thesecond component within the inner tubular wall of the container, has 3weight units of a 50 percent benzoylperoxide paste. A third component ina third tubular foil compartment contains 8.6 weight units of apropellant.

The proportions of the components in the above examples are notcritical, and can be varied.

When the bore is upward slanted, it is advantageous to thicken andthixotropicly adjust the mixture by addition of suitable powderyadditives, such as rock powder, soot, aerosil, talcum, kaolin, orasbestos flakes, so that the flowing out of the mixture during themixing and foam formation is reduced. Such a mixture is set forth in thefollowing example, but the ratios are not critical and may be varied.

EXAMPLE 3 The first component in the outer annular compartment of thecontainer consists of 100 weight units of a polyalcohol, 17.5 weightunits of castor oil, and 2.1 weight units of water. Asbestos flakes andaerosil are added to the components until the same is thixotropic. Thesecond component in the inner compartment consists of a diisocyanate.

It is possible to close the entrance opening of the bore after insertionof the rod, by wooden plugs or other mechanically or hydraulicallyexpansible closures. However, in accordance with the present invention,this is obtained by using a special container which is inserted afterthe first container, and placed at the entrance opening of the bore. Thesecond container has two compartments filled with the components of arapidly hardening resin-forming or foam-forming mixture. When the secondcontainer is broken together with the first container, resin or foamforms at the entrance opening of the bore and hardens quickly before thefoam in the inner part of the bore has filled the bore and fully formedand has hardened. In this manner, the foam developing from thecomponents inserted with the first container, is prevented to flow outof the entrance opening of a upward slanting bore, since a hard plug isformed at the entrance of the bore. In this manner, in accordance withthe invention, the step of closing the bore need not be separatelycarried out by a plug.

The following example concerns a foam-forming, rapidly hardening resinmixture which is used for plugging the entrance of the bore.

EXAMPLE 4 The plugging container is also made of two tubular wallsforming an outer and an inner compartment. The first component is placedin one of the compartments, and consists of 28 weight units of a cold,hardening, unsaturated polyester resin, and of 70 weight units of rockpowder and aerosil. The second component in the other compartmentconsists of a peroxide.

The reinforcing rods preferably consist of wood having a profiled crosssection, which may be square, rectangular, or otherwise non-circular.The leading end of the rod is sharpened or pointed to cut and break theplastic foil container easily. When the rod is quickly rotated, a mixingefi'ect is obtained which has been found entirely sufficient, if therotation is fast enough. Drilling machines may be used for rotating therod, particularly rotary-drilling machines of conventional construction,which are provided with a chuck for clamping the rod.

It is advantageous to cover the sharpened end of the rod with a metal orplastic fitting which reliably assures the breaking of the plastic foilcontainer walls.

Particularly if thickened resin mixtures are used, it is particularlyadvantageous to attach an agitating tool consisting of metal orsynthetic plastic material to the leading end of the rod so that themixing effect of the rotated rod is improved.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic side viewillustrating a container with two compartments, in accordance with theinvention;

FIG. 2 is a perspective view illustrating a first embodiment of the rod;

FIG. 3 is a fragmentary perspective view illustrating a secondembodiment of the rod used in the method of the invention; and

FIG. 4 is a perspective view illustrating a third embodiment of the rodprovided with an agitating tool.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, acontainer 1 is made of synthetic plastic foil material, and includes anouter tubular wall 2, an inner tubular wall 3, and clips 6, closing theends of the tubular walls 2 and 3, so that an outer annular compartment4 is formed between walls 2 and 3, and an inner compartment is formedwithin the inner wall 3. Container 1 is elongated and slender, and canbe longitudinally inserted into a drilled bore.

A first embodiment of the rod 7 is shown in FIG. 2. Rod 7 has a squarecross-section schematically indicated at 8, and has a slanted end faceforming a cutting edge 9. In the embodiment of FIG. 3, the rod 7 has aleading end covered by a fitting 10 having a pyramid-shaped pointed endportion 1 l.

Fitting 10,11 may consist of metal or a hard plastic synthetic material.It is evident that insertion of one of the rods 7, shown in FIGS. 2 and3, into a bore in which container 1 is located, will cut up and breakthe plastic foil walls of the container 1 which will cause thecomponents of the resin mixture to mix and foam, and then harden in thebore.

The embodiment of the rod 7 shown in FIG. 4 is provided with a fitting10' to which an agitating tool consisting of two blades 12 and 13 issecured so that rotation of rod 7' causes thorough mixing and agitationof the components flowing out of the broken container when rod 7 isrotated.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofmethods for reinforcing loose rock differing from the types describedabove.

While the invention has been illustrated and described as embodied in amethod for reinforcing loose rock by inserting into a hole drilled inthe rock, a breakable container having two compartments for thecomponents of a foam-forming mixture, and then breaking the container,it is' not intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can be applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention,and therefore such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:

1. A method for reinforcing loose rock, comprising drilling into therock at least one bore having a closed bottom portion and an entranceopening on the rock surface; inserting a breakable container into saidclosed bottom portion spaced from said entrance opening, said containerhaving at least two separate compartments filled with two components,respectively, which form a resinous hardenable expanding foamingmixture, when mixed; breaking said container in said bottom portion toestablish communication between said compartments so that saidcomponents mix in said bottom portion of said bore; and closing saidentrance opening before said mixture fully expands and hardens so thatsaid mixture is confined and enclosed within a closed space in said borewhile expanding, said mixture expanding and filling said closed space tosaid closed entrance port and entering under pressure between loose rockportions surrounding said bore whereupon said mixture hardens so thatthe rock around said bore is reinforced.

2. The method of claim 1 wherein said breaking of said container iscarried out by inserting a rod into said bore after insertion of saidcontainer into said bottom portion, said rod having a lengthcorresponding to the depth of said bore so as to leave said entranceopening free for closing so that after closing of said entrance bore,said rod remains in said bore for reducing the free volume of said bore.

3. The method of claim 1 wherein the step of closing said entranceopening includes the steps of inserting an other container into saidentrance opening after inserting of said container into said bottomportion of said bore, said other container having at least twocompartments filled with substances, respectively, which form, whenmixed, an other mixture which hardens quicker than said foaming mixture,and breaking said other container when breaking said container in saidbottom portion of said bore so that said other mixture is formed whichquickly hardens in said entrance opening to close said entrance openingbefore said foaming mixt hfll add'thlsdb.

T l 'i e b me tfi o i c laiir i 2 v vlie e in said rod consists of woodand has a non-circular cross section; and wherein the leading end ofsaid rod is shaped for cutting said container.

5. The method of claim 4 wherein said leading end of said rod has asharp metal or plastic fitting.

6. The method of claim 2 wherein said rod has an agitating meansattached to the leading end thereof, and including the step of turningsaid rod with said agitating means in said bore for mixing saidcomponents.

7. The method of claim 2 wherein said container includes an outertubular wall, an inner tubular wall in said outer tubular wall havingthe same length, and clips closing the ends of said tubular walls at theends of said container; and wherein one of said compartments in formedin said inner tubular wall, and the other compartment is formed withinsaid outer tubular wall and around said inner tubular wall.

8. The method of claim 7 wherein said inner and outer tubular wallsconsist of synthetic plastic foils adapted to be pierced and broken bysaid inserted rod.

9. The method of claim 1 wherein said mixture includes polyurethanes andwater.

10. The method of claim 1 wherein said mixture includes a polyester anda propellant.

11. The method of claim 1 wherein said mixture includes in addition tosaid components, a thickening powder for thixotropicly adjusting saidmixture.

12. The method of claim 11 where said thickening powder is a mineralpowder selected from the group consisting of rock-powder, aerosil,talcum, kaolin and asbestos flakes.

1. A method for reinforcing loose rock, comprising drilling into therock at least one bore having a closed bottom portion and an entranceopening on the rock surface; inserting a breakable container into saidclosed bottom portion spaced from said entrance opening, said containerhaving at least two separate compartments filled with two components,respectively, which form a resinous hardenable expanding foamingmixture, when mixed; breaking said container in said bottom portion toestablish communication between said compartments so that saidcomponents mix in said bottom portion of said bore; and closing saidentrance opening before said mixture fully expands and hardens so thatsaid mixture is confined and enclosed within a closed space in said borewhile expanding, said mixture expanding and filling said Closed space tosaid closed entrance port and entering under pressure between loose rockportions surrounding said bore whereupon said mixture hardens so thatthe rock around said bore is reinforced.
 2. The method of claim 1wherein said breaking of said container is carried out by inserting arod into said bore after insertion of said container into said bottomportion, said rod having a length corresponding to the depth of saidbore so as to leave said entrance opening free for closing so that afterclosing of said entrance bore, said rod remains in said bore forreducing the free volume of said bore.
 3. The method of claim 1 whereinthe step of closing said entrance opening includes the steps ofinserting an other container into said entrance opening after insertingof said container into said bottom portion of said bore, said othercontainer having at least two compartments filled with substances,respectively, which form, when mixed, an other mixture which hardensquicker than said foaming mixture, and breaking said other containerwhen breaking said container in said bottom portion of said bore so thatsaid other mixture is formed which quickly hardens in said entranceopening to close said entrance opening before said foaming mixture hasfully expanded in the closed bore.
 4. The method of claim 2 wherein saidrod consists of wood and has a non-circular cross section; and whereinthe leading end of said rod is shaped for cutting said container.
 5. Themethod of claim 4 wherein said leading end of said rod has a sharp metalor plastic fitting.
 6. The method of claim 2 wherein said rod has anagitating means attached to the leading end thereof, and including thestep of turning said rod with said agitating means in said bore formixing said components.
 7. The method of claim 2 wherein said containerincludes an outer tubular wall, an inner tubular wall in said outertubular wall having the same length, and clips closing the ends of saidtubular walls at the ends of said container; and wherein one of saidcompartments is formed in said inner tubular wall, and the othercompartment is formed within said outer tubular wall and around saidinner tubular wall.
 8. The method of claim 7 wherein said inner andouter tubular walls consist of synthetic plastic foils adapted to bepierced and broken by said inserted rod.
 9. The method of claim 1wherein said mixture includes polyurethanes and water.
 10. The method ofclaim 1 wherein said mixture includes a polyester and a propellant. 11.The method of claim 1 wherein said mixture includes in addition to saidcomponents, a thickening powder for thixotropicly adjusting saidmixture.
 12. The method of claim 11 wherein said thickening powder is amineral powder selected from the group consisting of rock-powder,aerosil, talcum, kaolin and asbestos flakes.